Southern California -- this just in

The men riding in the van with a U.S. government license plate all had military-style haircuts and the name tag "Perez" on the their camouflage uniforms.

But they immediately aroused the suspicion of authorities, who began asking questions when they arrived at a U.S. Border Patrol checkpoint last week east of San Diego.

In the end, officials concluded they were dealing with 13 illegal immigrants who had disguised themselves as U.S. Marines –- even donning battle dress uniforms and caps.

Such ploys have a long history along the border. Over the years, immigrants have disguised themselves as hard-hatted contractors and utility repairmen, and smugglers have painted and placed decals on cars to look like Border Patrol or other government vehicles.

The driver of the white van and another man, both U.S. citizens, were arrested March 14 at the Interstate 8 checkpoint near Campo and charged with alien smuggling, according to Border Patrol officials.

Three of the suspected illegal immigrants were detained as witnesses, while the rest were returned to Mexico, officials said.

The van drew suspicion in part because it had an altered U.S. government license plate, authorities said.